Vacuum bias switch

ABSTRACT

In the operation of the spark advance control system of an internal combustion engine, a vacuum bias switch is inserted in the vacuum line to the vacuum motor of the spark advance control unit to switch the line between different sources of vacuum during engine operation. The vacuum bias switch is responsive to one vacuum source generated at the carburetor up to a predetermined vacuum and then maintains that vacuum level until a second vacuum source exceeds the level. At that time, the vacuum bias switch connects the second vacuum source to the vacuum motor. The switch is a bi-directional switch in that it operates in both increasing and decreasing vacuum pressures. The structure of the switch completely isolates the two vacuum sources from each other.

United States Patent [191 Martin et al.

[ VACUUM BIAS SWITCH [75] Inventors: Frank J. Martin; Robert W.

Eshelman; Rudolph Bergsma, all of Ann Arbor, Mich.

[73] Assignee: Chrysler Corporation, Highland Park, Mich.

[22] Filed: Dec. 1, 1972 211 Appl. No.: 311,181

[52] US. Cl 137/119, 123/117 A, l37/DlG. 8 [51] Int. Cl. F02p 5/10 [58] Field of Search 137/118, 119, DIG. 8; 123/117 A [56] References Cited UNITED STATES PATENTS 3,476,094 11/1969 Rucins et al. 123/117 A X 3,021,828

2/1962 Frank 123/117 A [451 Apr. 16, 1974 Primary ExaminerRobert G. Nilson 5 7] ABSTRACT In the operation of the spark advance control system of an internal combustion engine, a vacuum bias switch is inserted in the vacuum line to the vacuum motor of the spark advance control unit to switch the line between different sources of vacuum during engine operation. The vacuum bias switch is responsive to one vacuum source generated at the carburetor up to a predetermined vacuum and then maintains that vacuum level until a second vacuum source exceeds the level. At that time, the vacuum bias switch connects the second vacuum source to the vacuum motor. The switch is a bi-directional switch in that it operates in both increasing and decreasing vacuum pressures. The structure of the switch completely isolates the two vacuum sources from each other.

7 Claims, 8 Drawing Figures 4 a 7 5 W 4 z r /M Z I j fl 1/ A? id VACUUM BIAS SWITCH SUMMARY OF THE INVENTION This invention relates to vacuum switches in general and particularly to a vacuum bias switch as used in emission control systems.

In the field of motor vehicle emissions control, the use of different vacuum sources for controlling the ignition timing operation of the engine has become necessary in order to enhance engine performance and decrease emission pollution. Depending upon the vehicle engine system, the different sources of vacuum are taken from various ports in the carburetor or various valves in the engine block.

It is a principle object of the invention to interconnect a vacuum line controlling the spark advance vacuum motor with .a first vacuum source up to a predetermined vacuum level and then maintaining that level until it is exceeded by the vacuum from a second vacuum source.

It is another object of the invention to prevent fluid communication among input ports ofa multi-input port vacuum switch.

It is yet another object of the invention to integrate a vacuum level calibration means and a fluid port communicator into a single unit thereby eliminating a source of fluid leaks within the device.

These and other objects will become apparent from the following drawings, description and claims of a vacuum bias switch having a multi-chamber housing. Each chamber is interconnected with an adjacent chamber for fluid communication therebetween and in addition several chambers have fluid communication ports between the chamber and an external means. A vacuum limiter valve controls the fluid communication between a first and second chamber.

The fluid communication port of the first chamber is connected to a first source of vacuum and the vacuum limiter valve functions to maintain the vacuum in the second chamber identical to said first source up to a predetermined vacuum level. A vacuum switch valve controls the fluid communication between a third chamber and the second chamber and operates to maintain the vacuum in the second chamber identical to the second vacuum source connected to the third chamber above the predetermined vacuum level defined by the vacuum limiter valve. Positioned within the communication ports which are in operative alignment with each of the valves is a vacuum valve calibration means operable with each valve for isolating said first and third chambers from inter-fluid flow.

DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 is a system schematic incorporating the carburetor and distributor of an internal combustion engine;

FIG. 2 is a .plan view of the vacuum bias switch; FIG. 3 is a section view taken along line 3-3 of FIG. 2;

FIG. 4 is a plan view of a valve actuator;

FIG. 5 is an elevation view of the valve actuator of FIG. 4;

FIG. 6 is a plan view of the valve calibration means receptacle of the vacuum bias switch of FIG. 2;

FIG. 7 is a partial sectional view taken along line 77 in FIG. 6;

FIG. 8 is a vacuum-speed graph of the vacuum sources of FIG. 1.

DETAILED DESCRIPTION Referring to the figures by the characters of reference, there'is illustrated in FIG. 1 a schematic of a spark advance control system as may be used in an internal combustion engine. The spark advance mechanismfllhe .distr miter Q is .pp r vtqdtbya sasuum motor 12 connected by a vacuum line 14 to the output port 16 ofa vacuum switch 18. The input ports 20 and 22 to the switch are connected by a pair of vacuum lines 24 and 26 that originate at the carburetor 28. One of the vacuum lines 26 is connected to the venturi section of the carburetor 28 andthe other vacuum line 24 is connected to the ported spark port of the carburetor 28 at a point above or on the air cleaner side of the throttle plate 30. The vacuum switch 18 connects either of the two input vacuum lines 24 or 26 to the spark advance vacuum motor 12 of the distributor 10 at predetermined vacuum conditions.

The vacuum switch 18 of FIG. 1 operates according to the graph of FIG. 8 which is a plot of vacuum in inches of mercury along the ordinate and engine speed along the abscissa.

The first source of vacuum is the vacuum adjacent the throttle plate 30, conventionally referred to as the ported spark vacuum. The curve 32 indicates that as the speed increases from idle, represented as the origin of the graph, the vacuum rises rapidly from zero vacuum and then falls off as the throttle approaches a wide-open position.

The second curve 34 on the graph of FIG. 8 represents the second source of vacuum or the venturi vaccum which indicates that for low engine speed ranges, the vacuum at this point in the carburetor is very low and is essentially at atmospheric pressure and as the throttle opens, the venturi vacuum increases due to the presence of the manifold vacuum and the flow of air into the carburetor 28. I

The third curve 36 on the graph of FIG. 8 indicated by a series of Xs, represents the output of the vacuum switch 18 and illustrates the switch following the first vacuum source to a predetermined vacuum level 38. The switch maintains its output at this level which is a bias level, until the second vacuum source exceeds the bias level. When the second vacuum source exceeds the bias level, the output of the switch 18 follows the vacuum of the second vacuum source.

The switch 18 as indicated in FIG. 1 comprises at least three vacuum chambers 40, 42 and 44 wherein a first vacuum chamber 40 is connected in fluid communication through a port 20 with an integral nipple extension 46 to the first source of vacuum. A third vacuum chamber 44 is connected in fluid communication through another port 22 with an integral nipple extension 48 to the second source of vacuum. The second vacuum chamber 42 is connected through a port 16 and an integral nipple extension 50 to a vacuum utilization means such as the spark advance control of the distributor 10. Internally of the switch, the second vacuum chamber 42 is connected through ports 81 and 85 for controlled fluid communication between either the first 40 or third 44 vacuum chambers. As will hereinafter be shown, there is no simultaneous fluid communication between the first 40 and third 44 vacuum chambers.

A vacuum limiter valve 52 controls the fluid communication between the first 40 and second 42 vacuum chambers and operates for maintaining the vacuum in the second chamber 42 within a predetermined vacuum range. A vacuum switch valve 54 controls fluid communication between the third 44 and second 42 chambers and operates maintaining the vacuum in the second chamber equal to the vacuum connected to the port 48 of the third chamber when that vacuum exceeds the predetermined range as defined by the vacuum limiter valve 54.

The vacuum bias switch 18 in the preferred embodiment is'molded in three sections, a top cover 56, a middle chamber member 58 and a bottom cover 60. The orientation of the switch as respects top and bottom is arbitrary as the switch will operate in any position.

. Referring to FIG. 2 there is illustrated a plan view of the preferred embodiment of the vacuum switch 18 of FIG. 1. The several apertures 62 in the top cover 56 provide passages for atmospheric pressure to be applied to a diaphragm 64 or valve actuation means within the valve switch.

FIG. 3 illustrates a sectional view taken along line 3--3 of FIG. 2 and illustrates the multi-chamber housing of the preferred embodiment of the vacuum switch. The right hand protion of FIG.. 3 illustrates the input port from the first vacuum source into the first vacuum chamber 40 and the vacuum limiter valve 52 controlling the fluid flow through the port 81 between the first 40 and second 42 chambers. The left hand portion of FIG. 3 illustrates the input port 22 from the second vacuum source entering into the third vacuum chamber 44 and the vacuum switch valve 54 controlling fluid communication through the port 85 between the third 44 and second 42 vacuum chambers. The output port 16 of the third vacuum chamber 42 is positioned in operative alignment with the vacuum switch valve 54 as will hereinafter be explained. v

As previously indicated, the top cover 56 has a plurality of apertures 62 which allow atmospheric pressure or ambient pressure to be applied to the switch. Along the interior of the top cover 56 are a plurality oflimit members 66 cooperating with diaphragm 64 to maintain a fourth or ambient pressure chamber 68. The limit members 66 prevent thediaphragm 64 from sea]- ing against the inside of. the cover 56 and blocking the apertures 62.

Positioned across the top of the middle chamber member 58 sealed thereto and spaced from the top cover 56 is the diaphragm member 64. The diaphragm cooperates with the normally open vacuum limiter valve 52 for permitting fluid communication between the first 40 and second 42 chambers. The diaphragm 64 also coooperates with the normally closed vacuum switch valve 54 for controlling fluid communication between the third 44 and the second 42 chambers when the vacuum in the third chamber 44 is equal to or greater than the vacuum in the second chamber. Limit means 70 are positioned in the middle chamber member 58 to limit the movement of the diaphragm 64 by atmospheric pressure. In addition, several ribs 72 are positioned in the third chamber 44 to prevent sealing of the diaphragm 64 to surfaces other than those surfaces which comprise the valve.

The bottom cover 60 cooperates with the middle chamber member 58 to define the first 40 and second 42 chambers and is selaed with the middle chamber member 58 to make the chambers air tight. Positioned along the bottom cover 60 are two ports 16 and 20 with integral nipple extensions 46 and 50 for connecting the first vacuum source to the switch 18 and for connecting the output of the switch to the vacuum utilization means 12. On the interior side of the bottom cover 60 and in alignment with each of the ports 16 and 20 is a threaded post means comprising four equal and equally spaced apart post sections 74. These post sections 74 are illustrated in FIGS. 6 and 7. An undercut flared passageway 76 provides unobstructed fluid flow from the nipples into or out of the chambers.

The middle chamber member 58 provides the side walls and one end wall of each of the three vacuum chambers. The first vacuum chamber 40. is defined by the two side walls 78 and 79, an end wall 80 containing a valve aperture or port 81 andis sealed by a flexible resilient member 82 cooperating with the bottom cover 60. The second vacuum chamber 42 is a bi-level chamber interconnected for fluid communication through a slot 84 in the wall separating the two levels. The third vacuum chamber 44 is defined by the diaphragm 64, an end wall 86 containing a valve aperture or port and two side walls 87 and 88 one of which contains the integral nipple extension 48 for attachment of a vacuum line 26 from the second vacuum source. Positioned in the valve apertures of the end walls of the first and third chambers are the vacuum limiter valve 52 and the vacuum switch valve 54.

Each of the two vacuum valves comprise a valve calibration means 90 and 92 supported within the ports 16 and 20 and integral nipple extension 50 and 46 of the first and second chambers, a calibrated valve spring 92 and 93 which is calibrated according to the vacuum level of the valve operation and a valve actuator 94 extending through the valve apertures and in contact with the diaphragm 64.

The valve calibration means 90 and 91 are illustrated as threaded members operating through a drawn conical bracket 96 for controlling the normal length of the valve spring 92 and 93. The threaded members 90 and 91 are positioned in the ports 46 and 50 to the chambers 40 and 42 thereby eliminating a source of valve leakage. The threaded members 90 and 91 are each supported by the four equal and angularly spaced apart post sections 74 extending into the valve chambers from the bottom cover 60. As illustrated in FIG. 7, fluid flow is through the port and between each of the posts by means of the flared passageway 76 and is unobstructed by either the threaded members 90 and 91 or the spring member bracket 96.

The calibrated valve springs 92 and 93 are designed for a given vacuum level and cooperate with the diaphragm 64 for opening or closing the valve. In the limiter valve 52, the spring 92will keep the valve open until a predetermined vacuum level when it will yield under the pressure applied by the diaphragm 64 to close the valve. In the switch valve 54 the spring 93 will keep the valve closed until a predetermined vacuum level when it will yield under the pressure applied by the diaphragm 64 to open the valve.

The valve actuator 94 as illustrated in FIGS. 3, 4, and 5 comprises a cup member 98 for retaining the valve spring 92 or 93 and a ribbed valve stem 100 ex- I tending co-axially in a direction away from the cup member. The outside diameter of the stem is approximately equal to the diameter of valve aperture between the chambers and the spaced apart ribs 102 provide fluid communication between the chambers. The peripheral surfaces of the stem guide the actuator as it moves through the aperture.

As previously indicated, the vacuum limiter valve 52 is normally open for fluid communication between the first 40 and second 42 vacuum chambers and cooperates with the atmospheric actuated diaphragm 64 for closing the valve 52 when the vacuum from the first source exceeds a predetermined vacuum level.

When the valve is closed, a metal plate 104 within the diaphragm seals with a stem portion 106 of a resilient umbrella valve 108 thereby preventing fluid communication between the two chambers.

When the vacuum in the second chamber 42 is greater than the vacuum in the first chamber 40, a vacuum release means or check relief valve 110, which is illustrated as an orifice between the two chambers, operates to break the seal formed by the umbrella valve 108 and the end wall 80 of the chambers. The vacuum release means 110 is not large enough for full fluid communication from the first chamber 40 to the second chamber 42; therefore, the port 81 must be opened as rapidly as possible. Therefore, when the seal is initially broken, the spring 92 will move the valve actuator 94 in a direction to lift the diaphragm 64 from the stem portion 106 of the umbrella valve 108 opening the port 81.

The operation of the vacuum switch valve 54 is similar to that of the vacuum limiter valve 52 with the exception that the valve is normally closed due to the sealing of the upper surface of the cup member 98 of the actuator 94 being pressed against a resilient circular valve seat 112. In the normally closed position, the spring 93 of the vacuum switch resists the pressure applied by the diaphragm 64 against the actuator to break the seal. When the vacuum from the second source is equal to or greater than the predetermined vacuum level, the diaphragm 64 under atmospheric pressure moves the valve actuator 94 to break the seal at the valve seat 112. When the seal is broken, the vacuum level in the second and third chambers equalizes to the vacuum of the second source.

The valve calibration means 90 and 91 located in the output ports of the first 40 and second 42 chambers is adjusted to prevent fluid communication between the first 40 and third 44 vacuum chambers. Thus, when the vacuum limiter valve 52 is open, the switch valve 54 is closed and conversely when the switch valve is open, the vacuum limiter valve is closed.

There has thus been shown and described a vacuum bias switch for supplying a vacuum utilization means with either of two vacuum sources. The switch comprises a vacuum limiter which bias the output of the switch from a first source until a second source exceeds the bias and then the switch connects the second source to the utilization means.

What is claimed is:

1. A vacuum bias switch comprising:

a multi-chamber housing wherein said chambers are interconnected for fluid communication between adjacent chambers and each chamber having at least one port for fluid communication into or out of said chamber;

a vacuum limiter valve positioned in a port between a first and second chamber for controlling fluid communication between said first chamber and second chamber, said limiter valve responsive to a first source of vacuum connected to another port of said first chamber for limiting a vacuum at the port of the second chamber when the vacuum of said first source is'below a predetermined vacuum level;

a vacuum switch valve positioned in a port between said second chamber and a third chamber for controlling fluid communication between said third chamber and said second chamber, said vacuum switch valve responsive to a second source of vacuum connected to another port of said third chamber for fluidly connecting said second source of vacuum to the port of said second chamber at said predetermined vacuum level whereby the vacuum at the port of said second chamber is substantially identical to said first source of vacuum up to said predetermined vacuum level and is substantially identical to said second source of vacuum beyond said predetermined vacuum level; and atmospheric valve actuation means cooperating with said vacuum limiter valve and said vacuum switch valve for sequentially operating said valves to eliminate fluid communication between said first and third chambers.

2. A vacuum bias switch according to claim 1 further including vacuum valve calibration means for said vacuum limiter valve and said vacuum switch valve and supported within ports which are in operative alignment with each valve said calibration means for controlling fluid communication between said second and saidfirst and third chambers.

3. A vacuum bias switch according to claim 2 wherein said vacuum limiter valve is normally open for fluid communication through said port between said first and second chamber and cooperates with said valve actuation means for closing said port between said first and second chambers when the vacuum level in said second chamber exceeds said predetermined vacuum level.

4. A vacuum bias switch according to claim 3 wherein said vacuum limiter valve comprises an inverted umbrella-shaped sealing member having a stem portion adapted to cooperate with said valve actuation means for sealing the port between said first and second second chamber and a vacuum release means for subsequently releasing said valve actuation means from said stem member when the vacuum in said first chamber is less than the vacuum in said second chamber for allowing full fluid communication from. said first to said second chambers.

5. A vacuum bias switch according to claim 2 wherein said vacuum switch valve is normally closed for fluid communication between said third and second chambers and cooperates with said valve actuation means for opening said port between said third and second chambers when the vacuum level in said third chamber is greater than said predetermined vacuum level.

6. A vacuum bias switch according to claim 1 wherein said valve actuation means is a flexible diaphragm member overlying said vacuum limiter valve and said vacuum switch valve and responsive to ambient pressure for sequentially actuating said valves.

7. A multiple port vacuum bias switch for switching the output port from one input port to another input port at a predetermined vacuum level, said switch comprising:

a first vacuum chamber connected in fluid communi cation through the one input port to a first source of vacuum;

a second vacuum chamber connected in fluid communication through the output port to a vacuum utilization means;

said first and second vacuum chambers interconnected through a port;

a third vacuum chamber connected in fluid communication through the other input port to a second source of vacuum;

said second and third vacuum chambers interconnected through a port;

first valve means interposed in said port between said first and second chambers for controlling the fluid communication therebetween;

second valve means interposed in said port between said second and third chamber for controlling the fluid communication therebetween whereby said said first and third chambers. 

1. A vacuum bias switch comprising: a multi-chamber housing wherein said chambers are interconnected for fluid communication between adjacent chambers and each chamber having at least one port for fluid communication into or out of said chamber; a vacuum limiter valve positioned in a port between a first and second chamber for controlling fluid communication between said first chamber and second chamber, said limiter valve responsive to a first source of vacuum connected to another port of said first chamber for limiting a vacuum at the port of the second chamber when the vacuum of said first source is below a predetermined vacuum level; a vacuum switch valve positioned in a port between said second chamber and a third chamber for controlling fluid communication between said third chamber and said second chamber, said vacuum switch valve responsive to a second source of vacuum connected to another port of said third chamber for fluidly connecting said second source of vacuum to the port of said second chamber at said predetermined vacuum level whereby the vacuum at the port of said second chamber is substantially identical to said first source of vacuum up to said predetermined vacuum level and is substantially identical to said second source of vacuum beyond said predetermined vacuum level; and atmospheric valve actuation means cooperating with said vacuum limiter valve and said vacuum switch valve for sequentially operating said valves to eliminate fluid communication between said first and third chambers.
 2. A vacuum bias switch according to claim 1 further including vacuum valve calibration means for said vacuum limiter valve and said vacuum switch valve and supported within ports which are in operative alignment with each valve said calibration means for controlling fluid communication between said second and said first and third chambers.
 3. A vacuum bias switch according to claim 2 wherein said vacuum limiter valve is normally open for fluid communication through said port between said first and second chamber and cooperates with said valve actuation means for closing said port between said first and second chambers when the vacuum level in said second chamber exceeds said predetermined vacuum level.
 4. A vacuum bias switch according to claim 3 wherein said vacuum limiter valve comprises an inverted umbrella-shaped sealing member having a stem portion adapted to cooperate with said valve actuation means for sealing the port between said first and second second chamber and a vacuum release means for subsequently releasing said valve actuation means from said stem member when the vacuum in said first chamber is less than the vacuum in said second chamber for allOwing full fluid communication from said first to said second chambers.
 5. A vacuum bias switch according to claim 2 wherein said vacuum switch valve is normally closed for fluid communication between said third and second chambers and cooperates with said valve actuation means for opening said port between said third and second chambers when the vacuum level in said third chamber is greater than said predetermined vacuum level.
 6. A vacuum bias switch according to claim 1 wherein said valve actuation means is a flexible diaphragm member overlying said vacuum limiter valve and said vacuum switch valve and responsive to ambient pressure for sequentially actuating said valves.
 7. A multiple port vacuum bias switch for switching the output port from one input port to another input port at a predetermined vacuum level, said switch comprising: a first vacuum chamber connected in fluid communication through the one input port to a first source of vacuum; a second vacuum chamber connected in fluid communication through the output port to a vacuum utilization means; said first and second vacuum chambers interconnected through a port; a third vacuum chamber connected in fluid communication through the other input port to a second source of vacuum; said second and third vacuum chambers interconnected through a port; first valve means interposed in said port between said first and second chambers for controlling the fluid communication therebetween; second valve means interposed in said port between said second and third chamber for controlling the fluid communication therebetween whereby said first and second valves are responsive to said first and second sources of vacuum respectively for providing fluid communication between said second chamber and either said first or third chamber; and valve actuation means overlying said first and second valves and responsive to ambient pressure for sequentially actuating said first and second valve means for inhibiting fluid communication between said first and third chambers. 